A swollen lump on the side of your neck could be something very serious and needs to be evaluated by a physician. If it is a lymph node from an infected tooth, usually the tooth and the lymph node will be painful, It can be a swollen lymph node from a serious condition such as lymphoma, a type of cancer. So please get this checked out.
It is possible that your neck swelling is related to a tooth infection. There is no way I can tell from here.
If you have a toothache, see a dentist, who can prescribe antibiotics if necessary, and extract the tooth if that is needed.